1. Technical Field
The present invention relates to a vehicle brake controller. Particularly, the invention relates to a vehicle brake hydraulic pressure controller capable of being mounted mainly to bar handle vehicles such an automatic two-wheel vehicle, an automatic three-wheel vehicle and an all terrain vehicle (ATV). Further, the present invention relates to a low pressure accumulator used in a vehicle brake hydraulic pressure controller having a brake system interposed by a pump.
2. Background Art
There is known a vehicle brake hydraulic pressure controller for controlling a brake force in interlocking brakes of a front wheel and a rear wheel of a vehicle such an automatic two wheel vehicle or the like by increasing a hydraulic pressure by a pump (e.g., Patent Reference 1: JP-A-2002-264787). The apparatus includes a stroke simulator for exerting an operation reaction force in accordance with an operation state of a brake operation element.
A vehicle brake hydraulic pressure controller disclosed in Patent Reference 1 includes an electric brake hydraulic pressure control mode and a mechanical brake hydraulic pressure control mode. In executing the electric brake hydraulic pressure control mode, an operation reaction force in accordance with an operation state of a brake operation element is exerted to the brake operator by operating a stroke simulator. Further, when an abnormality occurs in executing the electric brake hydraulic pressure control mode, a constituent element related to the electric brake hydraulic pressure control mode is made OFF, the mode is shifted to the mechanical brake hydraulic pressure control mode, and a failsafe function can be realized by directly supplying a brake fluid pressure in correspondence with a brake operating amount to a wheel cylinder.
Meanwhile, according to the vehicle brake hydraulic pressure controller of the background art, in order to achieve the operation reaction force in accordance with operation state of the brake operation element, the stroke simulator is provided with a dummy cylinder for storing a brake fluid. However, it is necessary to provide a predetermined volume for the dummy cylinder for achieving the predetermined operation reaction force. When the dummy cylinder is provided on a base member of the vehicle brake hydraulic pressure controller, there is a necessity to avoid interference with other members needing a volume such as a pump and there is a concern of making a total of the apparatus large-sized.
Furthermore, according to a vehicle brake hydraulic pressure controller of a background art, when normal pressure increasing is carried out, there is carried out a control of applying a brake fluid pressure to a wheel brake by shutting off a flow path communicated with the wheel brake (wheel cylinder) from a master cylinder constituting a hydraulic pressure source and operating a pump provided at a hydraulic pressure circuit.
At this occasion, the brake fluid necessary for increasing the pressure stored to a reservoir tank is used, and the brake fluid stored to the reservoir tank is sucked to a pump to supply to the side of the wheel brake (e.g., Patent References 1 and 2; Patent Reference 2: JP-A-8-324406).
Meanwhile, in a vehicle of a bar handle type such as an automatic two wheel vehicle, an automatic three wheel vehicle, an all terrain vehicle (ATV), from a viewpoint of an installing space of the vehicle, a reservoir tank is attached to a bar handle, however, when such a mode is adopted, there is a concern of complicating attachment of a pipe. Therefore, it is desired to separately provide a reservoir tank capable of storing the brake fluid.
Hence, it is conceivable to provide the reservoir tank to a modulator (base member) or the like constituting a vehicle brake hydraulic pressure controller. However, the base member is provided with pluralities of flow paths and member mounting holes for carrying out a brake hydraulic pressure control, when the reservoir tank is going to be provided by avoiding the flow paths and the member mounting holes, there poses a problem that the base member itself becomes large-sized.